Javascript单击多个按钮之一

Question

There are two buttons present in a form, and I would like to use GreaseMonkey to automatically click one of the buttons when the page loads. The two buttons are:

<td rowspan="2"><input class="first action" name="first" type="submit" value="First Action" style="font-size: 10pt;" /></td>
<td rowspan="2"><input class="second action" name="second" type="submit" value="Second Action" style="font-size: 10pt;" /></td>

I have tried the two below codes, but neither are working. The first selects the form and tries to submit it, and I get an error that says "No Action Permitted." The second tries to click() the button.

First:

var button = document.getElementById('units_form');
window.location(button);

Second:

var button = document.getElementByClassName('first action');
button.click();

Answer 1

First off, the generic solution:

• to get an element object by class name, use document.getElementsByName("class_name")[0] . The last part [0] gives you the first of all elements that have this class
• To fire an event on element, see this article on MDN . I strongly advise to read it all . Judging from your post you're quite lazy when it comes to reading articles.

Putting it all together:

var button_element = document.getElementsByName("button-class-name")[0];
var event_object = new MouseEvent('click', {
    'view': window,
    'bubbles': true,
    'cancelable': true
});
button_element.dispatchEvent(event_object);

Also, most sites use jQuery library, for which it boils down to:

$(".class_name").click();

Note that this will fire on all elements with that class name.